A. Field of the Invention
The present invention generally relates to a new and improved lancing device for puncturing the skin of a user to obtain a blood sample. More particularly, the present invention relates to a new and improved lancing device with an automatic cocking feature.
B. Description of the Prior Art
Sharp pointed lancets are employed to make a puncture or penetration of a patient's skin in order to provide a small outflow of blood. Various tests may be employed with only small amounts of blood so that blood flowing from a finger prick is normally sufficient for these tests. Tests on the blood sample often include contacting a paper strip or reagent pad on a strip carrying chemistry with blood from the wound or puncture.
Known lancet assemblies utilize a hammer or gripper that engages or strikes a lancet and drives the lancet into the skin of a patient or user. By cocking the hammer or gripper, the user compresses a spring that stores energy. As the user cocks the hammer or gripper, the hammer or gripper is latched in position and held in place until the user pushes a firing button. Pushing the firing button releases the hammer or gripper. The hammer or gripper is then driven from its cocked position under the biasing force of the spring to drive the lancet into the patient's skin.
Before the lancet assembly can be used again, the patient or user must cock the hammer or gripper. Current cocking methods require twisting a cap or moving a spring-loaded knob into the cocked position. The device is then cocked and ready to fire. Unfortunately, external cocking methods require extra operating steps, and, unless the lancet assembly utilizes some method to indicate that the device is cocked and ready to fire, the user could be unsure as to whether the lancet assembly is cocked and could accidently fire the lancet while attempting to cock the hammer or gripper. Moreover, current lancing devices can be prematurely fired by just handling the cocked unit. This is because the firing spring is compressed, and the firing button has a short release stroke.
Current lancet assemblies include two separate components. a reusable base unit and a disposable end cap. An example of such a lancet assembly is disclosed in U.S. Pat. No. 4,990,154, herein incorporated by reference. The end cap is designed to house a lancet, and the base unit houses a hammer that engages or strikes the lancet and drives the lancet into the skin of the patient or user. The hammer acts as a striking element rather than a gripping structure and includes a striking face. The base unit, similar to other prior art lancet assemblies, requires the user to push the hammer into the base unit. As the hammer moves into the base unit, a spring compresses to store energy, and the hammer is latched into a cocked position until the firing button is pressed. After firing, this lancet assembly requires the user to recock the base unit.
Thus, a need exists for an lancing device with an automatic cocking feature so that the lancing device is always cocked and ready to fire. A need also exists for a lancing device which does not fire accidently and does not misfire.